Door chain lock



1954 J. ADAMEC ETAL 3,161,035 DOOR CHAIN LOCK Filed June 28, 1961 I92 l9 I Q 2o J I 2| FIGJ 22 25 I 5 I 25 32 O 27 27 I4 3| I8 29 30 I6 23 H 42 4| F 4 23 22 24 23 7 f 4 "5 24 FIGS 2| 4-6 24 24 23 3o 45 L 4| 23 4725 2 5 I" 29 [8 42 46 4 INVENTORS I ROBERT J. BRADLEY FIGS BY JOSEPH ADAMEC' United States Patent Office 3,li,35 Patented Dec. 15, 1964 This invention relates to door chain locks which may be engaged to hold a door by means of the chain in a partially opened and yet secure position, and also released to release the door so that it may be fully opened, and in which an operator may engage or release the said door chain lock from either side of the door, and in which a key is required to operate a release mechanism to release the said door chain lock from a position outside the door.

Door chain locks which hold a door securely in an open position approximately 2" or 3" or so to permit a person on the inside to communicate with someone on the outside, and yet securely hold the door from opening any further are well known in the art and need no further description.

There have even been door chain locks in the prior art in which both ends of the door chain are releasable so that the chain may be removed from the door by a person outside the door with a key to operate a lock mechanism to release the chain from the door frame at such time whenthe chain is engaged both to the door and to the door frame and the door is ajar, being held approximately 2" or 3" in open position by the chain.

from the bracket 10 only when it is in the vicinity of the keyhole l2.

The other end of the chain 14 is attached to a locking slide 16 which is adapted to fit into locking slide receiving means 17 in door frame attachment means such as a housing frame 18. The bracket lit, as well as the housing frame 18, are secured to the door and to the door frame respectively by means of screws 19, or by any other means of fastening. 'While it is preferred to attach the bracket 10 to the door and the housing frame 18 to the door frame, it is to be understood that element, 18 may be attached to the door and element 19 may be attached to the door frame, and vice versa.

The locking slide 16 has a bevelled portion 20 to facilitate insertion into the locking slide receiving means 17 of the housing frame 13, There is also striker means such as the Wall 21 of a recessed portion 22 in the locking slide, which cooperates with the nosed portion 23 of latch bolt 24. Slide stop means 25 in the form of a shoulder are provided to 'engagethe downwardly facing portion as of the housing to limit the movement of the locking slide 16 into the'housingQ Outward movement of the locking slide 16 is prevented by engagement of nose 23 of latch It is an object of this invention to provide an improved 7 door chain having key and lock means which releasably secure one end of the chain to the door frame which is strong and durable and positive acting. It is a further object of this invention to provide such a door chain in whichthe screws, or other means for fastening the latching means to the door frame, will be covered when the chain is in locked position sothat the door frame attachment cannot be removed by any intruder.

Further objects and advantages will appear from the specification hereinbelow. We achieve these objects and advantages with the device illustrated in the accompanying drawings in which:

'FIG. 1 is a front elevation of portions of a door and a door frame with our invention installed, and with the locking slide suspended immediately below the door frame attachment means prior to its insertion for locking;

FIG. 2 is a cross section along the lines 2-2 in FIG. 1;

FIG. 3 is a medial cross section of a housing frame of thedevice with the locking slide in locked position;

FIG. 4 is a cross section of the entire housing frame as seen from a position along the lines 4-4 of FIG. 3;

FIG. 5 shows a side view of the latch bolt; and

FIG. 6 shows the opposite side of the latch bolt shown in FIG. 5.

Similar numerals refer to similar parts throughout the several views.

Our invention is made preferably of metal such-as steel. However, it may be made of any other material strong enough for the purpose. 7

We provide door attachment means such as a plate or bracket MP, of the usual type, which is attached or secured to the door 11. The bracket to has a keyhole iZ'and a slotway 13. There is a chain 14 which has keying means, such as the usual sliding key 15, attached to one end thereof. (not shown) which fits into the keyhole l2 and a reduced portion (not shown) which will fit within the slotway 13 The usual sliding key 15 has a wide portion in such manner that the sliding key can be removed bolt 24 against striker portion 21 of the locking slide 16. The, locking slide/i6 is attached to chain 14 by means of a rivet 27 or by any other suitable means. We also provide a fiat spring .28 which is pressure fitted into spring seats 29 at its ends 30. The purpose of the spring 28 is to provide pressure means to act in concert with the slide fitting of the locking slide into the locking slide re ceiving means to prevent unnecessary slipping of the locking slide, and also to help to guide the locking slide in place into lock position. v

The housing frame 13 has a lock receiving portion 30 into which a cylinder lock 31 having key operating means 32 is fitted. The cylinder lock 31 is held in place by means of a spring pressured pin or other detent means 33 which will slide into opening 34 in the frame 18. The lock 31 may be removed by placing a narrow pin or rod into opening 34 and pushing pin or detent 33 back into the look. This permits the lock to be removed. The lock 31 has a latch bolt pin which moves when the lock is operated. For example, lock 31 as shown in the drawings is a rotatable cylinder lock, and latch bolt pin ill will rotate When key 32 is inserted to rotate the cylinder lock 31. Rotation will be in the direction of the curved arrow shown in FIG. 4 of the drawings.

Latch bolt 2 4 has a recess 41 adapted to receive the latch bolt operating pin 4% As the latch bolt operating pin 5%) rotates, it will move toward wall 42 of the recess 41 until it engages wall 42. Itwill then move the entire bolt 2d in the direction of the direction of the straight arrow shown in FIG. 4. At the point when nose portion 23 of latch bolt 24 clears the locking slide receiving means 17 of the housing frame 18, further rotation action is stopped by appropriate means such as stops, not shown, along the degree of rotation of the cylinder. For example, we have found that adegree of rotation of approximately to is sufficient to operate the latch bolt 'pin. to move the latch bolt out of locking slide receiving means 17. When manual pressure is removed from key- 32, latch bolt 24 is pushed back into the area of the locking slide receiving means 17 by means of a spring &5 which is seated against spring seat 46in latch bolt 24 and against portion 47 of housing frame 18.

Chain 14 is made long enough so that the door 11 can be opened for purposes of talking to someone on the outside or for receiving a small package or letter, and

yet must be short enough so that an unauthorized person on the outside may not be able to push the door open 3 Key slide 15 should be removable only when the door is at or near fully closed position.

It will be appreciated that when our invention is installed on a door and a door frame, it will secure the door within the limits described above, and yet permit a person having a proper key 32 to insert the key into the lock 31, inside the door frame, from a position outside the door. Key 32 can then be used to rotate lock 31, and in the manner described above, release locking slide 17 .by drawing latch bolt 24 away from striker 21. Locking slide 17 will then fall disengaging chain 14 from the door frame. If it is desired to lock the door chain from the outside, the chain is attached to bracket only by means of key slide 15. The door is then closed from the outside until the operator can only put his lower forearm between the door and the door frame. The operator then grasps the locking slide and pushes it up into housing frame 18. Thus, our invention can be locked from outside the door. If an unauthorized person should succeed in opening the regular door locks (which are not shown herein but which is assumed couldbe a part of the door locking equipment), the door will then be held by the chain. This will give the impression, even though the premises are unoccupied, that there should be somebody within the premises to have been able to lock the chain. Such knowledge is often sufficient to deter an unwanted intruder.

Another feature of our invention is the fact that when the locking slide 17 is in locked position, the upper portion 40 covers upper screw 19, and lower portion 41 covers lower screw 19 of housing frame 18, making it impossible for anyone to insert a screwdriver to remove screws 19 and take housing frame 18 off the door frame.

While we have described our invention in its preferred forms, there are other forms which it may take without departing from the spirit of the invention, and we, therefore, desire to be protected for all forms coming within the claims appended hereinbelow.

Wherefore we claim:

1. A door chain lock comprising chain means adapted to be fastened to a door and a door frame of a structure by fastening means to permit restricted opening of the said door, in which at least one of the said fastening means comprises: locking slide receiving means having a housing containing an opening therethrough and a transverse latch bolt reciprocably mounted so that a portion thereof may be moved from a first, locking position within the said opening to a second, unlocking position outside of the said opening, and means to fasten the said housing to a portion of the said structure; and a locking slide adapted to slide fit into said locking slide receiving means attached to the said chain means and having a cross sectional dimension in at least a portion thereof corresponding to the cross sectional dimension of the opening through the said locking slide receiving means, said locking slide having a recess in a position which is in faced relationship to the said latch bolt of the locking slide receiving means when the said locking slide is slide fitted into the locking slide receiving means, in which the said housing includes a key operated lock to operate the said transverse latch bolt, and is provided with at least one means to receive at least one fastener for mounting said housing; and in which the said locking slide, when fitted in the housing of said locking slide means, covers the said means to receive the fastener.

2. The door chain lockas defined in claim 1, in which the said locking slide has stop means incorporated therewith which cooperate with stop means incorporated in the said housing.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A DOOR CHAIN LOCK COMPRISING CHAIN MEANS ADAPTED TO BE FASTENED TO A DOOR AND A DOOR FRAME OF A STRUCTURE BY FASTENING MEANS TO PERMIT RESTRICTED OPENING OF THE SAID DOOR, IN WHICH AT LEAST ONE OF THE SAID FASTENING MEANS COMPRISES: LOCKING SLIDE RECEIVING MEANS HAVING A HOUSING CONTAINING AN OPENING THERETHROUGH AND A TRANSVERSE LATCH BOLT RECIPROCABLY MOUNTED SO THAT A PORTION THEREOF MAY BE MOVED FROM A FIRST, LOCKING POSITION WITHIN THE SAID OPENING TO A SECOND, UNLOCKING POSITION OUTSIDE OF THE SAID OPENING, AND MEANS TO FASTEN THE SAID HOUSING TO A PORTION OF THE SAID STRUCTURE; AND A LOCKING SLIDE ADAPTED TO SLIDE FIT INTO SAID LOCKING SLIDE RECEIVING MEANS ATTACHED TO THE SAID CHAIN MEANS AND HAVING A CROSS SECTIONAL DIMENSION IN AT LEAST A PORTION THEREOF CORRESPONDING TO THE CROSS SECTIONAL DIMENSION OF THE OPENING THROUGH THE SAID LOCKING SLIDE RECEIVING MEANS, SAID LOCKING SLIDE HAVING A RECESS IN A POSITION WHICH IS IN FACED RELATIONSHIP TO THE SAID LATCH BOLT OF THE LOCKING SLIDE RECEIVING MEANS WHEN THE SAID LOCKING SLIDE IS SLIDE FITTED INTO THE LOCKING SLIDE RECEIVING MEANS, IN WHICH THE SAID HOUSING INCLUDES A KEY OPERATED LOCK TO OPERATE THE SAID TRANSVERSE LATCH BOLT, AND IS PROVIDED WITH AT LEAST ONE MEANS TO RECEIVE AT LEAST ONE FASTENER FOR MOUNTING SAID HOUSING; AND IN WHICH THE SAID LOCKING SLIDE, WHEN FITTED IN THE HOUSING OF SAID LOCKING SLIDE MEANS, COVERS THE SAID MEANS TO RECEIVE THE FASTENER. 